KAC-9152D Kenwood - No Power

Hello DIYAUDIO community. I have been very pleased with the wealth of information available on this site. Lots of expert advice and patience with those of us who are not experts. I tried to do my homework so that patience can continue.

I am working with class D Amp that will not power on. I am bench testing with basic multimeter, car battery for 12V source with a 10A fuse in series.

I have attached a PDF doc that contains what I believe to be the most relevant components (with ref desig) for this type of repair. The measured Voltage for the 16 pins on the Driver IC is listed. Also, the measured ohms between leg 2 and 3 on the Output Transisters have been verified (not=0).

This is as far as I could get. Information overload kinda has my brain scrambled on the next step....

Thanks in advance for helping to steer me in the right direction. Let me know if theres missing info needed.
 

Attachments

  • KAC-9152D Repair Data.pdf
    108.7 KB · Views: 122
I usually check all the fets the ones clamped to the heatsink, and all their legs(1-2, 2-3). maybe there is an open short between legs one and two? Most often one of them is bad. and is not letting the amp power on. It could be one of the output fets is bad, and triggering the protection circuit to not let the amp power up as well.



If you and your pdf go over to the car audio section, you may get nelp from master yoda himself.
 
just read the website, and the basic amp part once and a while. Your probably trying to take to much in. I know my brain does the same thing all the time, especially trying to learn to read schematics.

When you get to the voltage regulators, and or current rectifiers. D18, and D20, I Dunno if they look like all the fets. You will get wild and crazy readings. your actually reading the windings of the power transformer.

Thats all I know for now till i remember something else.


If you can afford it, and wanna keep working on amps. I would highly recomend the tutorial. It enough information to keep your head overheating for years to come.
 
DC voltage on Q1 and Q2. Use the pin numbering scheme in the attached image.
 

Attachments

  • 2sc4081x.gif
    2sc4081x.gif
    15.9 KB · Views: 78
W114 qnd W122 voltages

W114 and W122 are marked on the board. Both are 4.27 volt at both ends.

Also, I went back and re-checked all my values with a new 12V supply battery.

Q3: 1) 12.2 2) 3.1 3) 11.6

D4: p-con side) 11.56 other) 4.88

Q1: 1) 4.3 2) 4.3 3) 4.87
Q2: 1) 4.3 2) 4.9 3) 11.25

IC1
1) 0 2) .05 3) .05 4) .1 5) .7 6) 1 7) 0 8) 3.1
9) .07 10) 2.6 11) 3.1 12) 3.1 13) 2.2 14) 2.2 15) 2.2 16) 0
 
After doing some more inspection, I've found a problem. There is either a broken trace or missing component at one end of W17. I have marked it's location with an arrow in the attached pic. It looks to me like something was there, but, I couldn't find anything on the schematics.

Sorry my inexperience is showing through.



moz-screenshot.png
moz-screenshot-1.png
 

Attachments

  • W17.JPG
    W17.JPG
    10.1 KB · Views: 63
After checking and re-checking the schematics, I concluded that it was only a broken trace. I re-flowed the trace and like magic....the amp powered on. I'll have to do some final testing later, but, I think we got it going.

Big thanks to Perry and Blakktalon for their expert assistance.

I now have another amp to start troubleshooting. This one I'll be able to take more time reading and learning on my own.